#!/bin/perl5 -w
# $Id: subst,v 1.2 1999-09-27 13:05:38-05 annis Exp $
# $Source: /u/annis/uw-unix/perltut/RCS/subst,v $
#
# Do a search and replace of all given files.
# ./subst /old/new FILE-0 FILE-1 ... FILE-N

use POSIX;
use strict;

# Get the replacement pattern: /old/new/
my $regexp = shift @ARGV;

# First, grab out the pattern.
my @rtmp = split(/\//, $regexp);
if ($#rtmp != 2) {
    die "Where is my regular expression?";
}
my $old = $rtmp[1];
my $new = $rtmp[2];

# We're going to keep all files in this temporary
my $temp = tmpnam();

# MAIN loop
foreach my $file (@ARGV) {
    if (! open(FH, "< $file")) {
        print STDERR "I can't open $file: $!\n";
        exit(1);
    } else {
        open(NEW, "> $temp") or die "Can't open $temp";
        my $move = 0;   # False

        while (<FH>) {
            if ($_ =~ s/$old/$new/g) {
                $move = 1;
            }

            print NEW $_;
        }

        close FH;
        close NEW;

        if ($move) {
            rename($file, "$file.bak") or die "Cannot rename $file";
            `mv $temp $file`;   # rename can't cross filesystems
            #rename($temp, $file) or die "Cannot copy $temp to $file: $!";
        }
    }
}

unlink($temp) or die "Unable to remove $temp: $!";




# EOF